Pressure-operated electrical high voltage circuit breaker

ABSTRACT

A receiving vessel for displaced hydraulic fluid is positioned at the cylinder of the drive mechanism of an electrical circuit breaker having a hydraulic drive. The receiving vessel is connected via a valve to the hydraulic system which includes a storage unit and a low pressure vessel. The connection is provided via a single pipeline between the receiving vessel and the hydraulic system. The valve connects the pipeline with either the receiving vessel or the cylinder, depending upon the pressure. The circuit breaker is especially suitable for high voltage, high capacity operation.

United States Patent [1 1 Priitsch et al.

[1 1 3,745,280 [451- July 10,1973

[ PRESSURE-OPERATEDv ELECTRICAL HIGH VOLTAGE CIRCUIT BREAKER [75] Inventors: Rudolf Priitsch; Helmut Beier; Klaus Diskar, all of Berlin, Germany [73] Assignee: Siemens Aktiengesellschait, Berlin and Munich, Germany [22] Filed: Dec. 13, 1971 [21] Appl. No.: 207,293

[30] Foreign Application Priority Data Dec. 18, 1970 Germany P 20 64 798.7

[52] [1.8. CI. 200/82 B, 200/148 E [51] Int. Cl. HOIh 35/38 [58] Field of Search 137/624.1l; 200/82 R, 82 B, 148 E [56] References Cited UNITED STATES PATENTS 2,748,226 5/1956 MacNeill 200/148 E FOREIGN PATENTS OR APPLICATIONS Primary ExaminerRobe11 K. Schaefer Assistant ExaminerGerald P. Tolin Alt0rney- Arthur E. Wilfond, Herbert L. Lerner et al.

[57] ABSTRACT A receiving vessel for displaced hydraulic fluid is positioned at the cylinder of the drive mechanism of an electrical circuit breaker having a hydraulic drive. The receiving vessel is connected via a valve to the hydraulic system which includes a storage unit and a low pressure vessel. The connection is provided via a single pipeline between the receiving vessel and the hydraulic system. The valve connects the pipeline with either the receiving vessel or the cylinder, depending upon the pressure. The circuit breaker is especially suitable for high voltage, high capacity operation.

7 Claims, 2 Drawing Figures PRESSURE-OPERATED ELECTRICAL HIGH VOLTAGE CIRCUIT BREAKER The present invention relates to an electrical circuit breaker. More particularly, the invention relates to an electrical circuit breaker with a hydraulic drive.

German Published Patent Application No. 1,286,610 discloses an electrical circuit breaker having a hydraulic drive mechanism which includes a cylinder at high voltage potential. A receiving vessel for displaced hydraulic fluid is provided at the cylinder. If there is a switching action or motion, the receiving vessel is connected to the cylinder via a control valve which is also at high voltage potential, so that hydraulic fluid may escape from the cylinder into the receiving vessel. The same valve also controls the connection to a hydraulic system at ground potential. The hydraulic system includes a storage unit, accumulator or storage tank and a low pressure vessel. Two pipelines are required for this connection. A high pressure pipeline leads from the storage unit to the control valve at high voltage potential and from there to the cylinder. A low pressure pipeline connects the receiving vessel, via the control valve, to a pump which has to fill up the storage unit.

In the known circuit breaker, the oil or fluid displaced from the cylinder may be conducted away without an appreciable increase in pressure, so that the switching process is not impeded. This advantage is provided, however, at considerable cost. The known control valve is a complicated multiplex valve and must be provided at high voltage potential. For this reason, two hydraulic lines must be run through the electrically highly stressed region between the high voltage and ground potential.

An object of the invention is to provide an electrical circuit breaker which overcomes the disadvantages of known circuit breakers of similar type.

Another object of the invention is to provide an electrical circuit breaker having a hydraulic drive, which circuit breaker is of considerably simple structure.-

Another object of the invention is to provide an electrical circuit breaker for rapid breaking without delay by displaced fluid.

Still another object of the invention is to provide an electrical circuit breaker of simple structure which functions with efficiency, effectiveness and reliability.

Yet another object of the invention is to provide an electrical circuit breaker having a hydraulic drive and a receiving vessel for displaced hydraulic fluid positioned at the cylinder of the hydraulic drive, to provide rapid breaking which is not delayed by the displaced fluid.

In accordance with the present invention, a receiving vessel is connected via a valve to the hydraulic system of a circuit breaker. The hydraulic system includes a storage unit and a low pressure vessel. A single pipeline is provided between the storage unit and the hydraulic system and is connected to either the receiving vessel or the cylinder, depending on the pressure in the pipeline.

In the electrical circuit breaker of the invention, the valve provided at the receiving vessel is a hydraulic switch which establishes a connection to either the cylinder or the receiving vessel, depending upon the pressure condition in the pipeline. The pressure condition in the pipeline depends upon whether or not the end of the pipeline away from the receiving vessel is connected to the storage unit via a control valve. For this reason, the control valve may be provided at ground potential, even if the cylinder is at high voltage potential, so that it is easy to operate, install and maintain. Most important, however, is the fact that a single pipeline is sufficient between the storage unit and the cylinder, which may be at high voltage potential, and the receiving vessel.

It may be of advantage to bridge the control valve by a pump. This permits the receiving vessel to be emptied as soon as it is connected to the hydraulic system when the pressure in the pipeline is zero. A check valve may be connected in series with the pump in order to prevent loading of the pump during the operating stroke of the drive.

It is of advantage to design the circuit breaker of the invention in such a way that a constantly acting disconnecting force may be released by connecting the cylinder to the receiving vessel, which is controlled by the valve. The constantly acting disconnecting force may be a spring force or the force of a constantly acting pressure medium which is maintained hydraulically in the one breaker position. If the drive is reversed by lowering the pressure, the cylinder is connected to the receiving vessel. The constantly acting force then forces the hydraulic fluid in the cylinder into the receiving vessel.

The unimpeded discharge of the hydraulic fluid displaced by the drive mechanism is particularly advantageous for electrical circuit breakers of several phases. Each phase may have a cylinder, a valve and a receiving vessel. The single pipeline of each phase is connected to the single storage unit of the circuit breaker via a control valve common to all phases. In this manner, all the phases have the same switching time for each stroke, regardless of the length of the pipeline between the cylinder and the storage unit so that, for example, the desired synchronism of the phases is provided without special adjustment in the important switching off operation.

In order that the invention may be readily carried into effect, it will now be described with reference to the accompanying drawing, wherein:

FIG. 1 is a schematic diagram, partly in section, of a three phase embodiment of the electrical circuit breaker of the present invention having a hydraulic drive; and

FIG. 2 is a sectional view, on an enlarged scale, of the receiving vessel of the hydraulic drive of the circuit breaker of FIG. 1.

In the FIGS., the same components are identified by the same reference numerals.

The electrical circuit breaker illustrated in FIG. I operates at kilovolts.

In FIG. 1, a circuit breaker 1 comprises three equal phase columns 2, 3 and 4. Each of the columns 2, 3 and 4 is identical to the others, so that only the column 2 will be described in detail. A breaker chamber 6 is supported by a standoff insulator 5 on the first phase column 2. The breaker chamber 6 has a fixed contact element 7 and a movable contact pin 8 therein. The movable contact pin 8 is afflxed to an actuator plunger or drive piston 9 which is provided in a cylinder 10 of a lower breaker part 11 of the column 2. A receiving vessel 12 is connected to the cylinder 10.

The pressure fluid of the hydraulic drive is supplied by a storage unit, accumulator or storage tank 14. The storage unit 14 is connected to the hydraulically parallel-connected drives of the individual phases via a common control valve 15. A pump 16 is connected in series with a check valve 17 and the series combination is shunted across the control valve 15.

A single pipeline 21 extends from the drive of the first phase column 2 to the control valve 15. A single pipeline 22 extends from the drive of the second phase column 3 to the control valve 15. A single pipeline 23 extends from the drive of the third phase column 4 to the control valve 15. A pressure-dependent valve 25, which is shown in detail in FIG. 2, is provided in each of the pipelines 21, 22 and 23. A movable valve member 26 is provided in the valve 25. The movable valve member 26 is movable under the action of a spring 27 to normally occupy a position in a cylinder 28 shown in FIG. 2.

In the position of the valve member 26 shown in FIG. 2, a valve seat 31 leading into the receiving vessel 12 is open or free. There is therefore a connection to a bore, aperture or duct 32 which opens into the cylinder 28, and, via a bore, aperture or duct 33, in the valve element 26 opening into the pipeline 21. The receiving vessel 12 is thereby normally connected to the pipeline 21. The pump 16 may thus draw hydraulic fluid from the receiving vessel 12 and force it into the storage unit 14 when the pressure in said storage unit drops.

If the circuit breaker is to close, the control valve 15 is opened. This causes the pressure medium or fluid which is under the pressure of the storage unit 14 to flow into the valve 25. When the fluid flows into the valve 25, it forces the movable valve element 26 upward, and said movable valve element closes off the valve seat 31. Simultaneously, the pressure medium or fluid flows through a duct, bore or aperture 35 and forces a spring-loaded valve head or cone 36 away from the opening of said duct, bore or aperture. This opens a path for the fluid to flow past the valve element 26 into a pipeline 37. The cylinder for the drive piston or plunger 9 of the circuitbreaker is connected to the pipeline 37. The circuit breaker is then closed and a disconnecting spring 38 (FIG. 1) is placed under tension.

In order to open the circuit breaker, the plunger or piston 9 is relieved of pressure by closing the valve 15. The disconnecting spring 38 then drives the contact pin 8 downward with the plunger or piston 9. The hydraulic fluid is thereby displaced. The displaced fluid flows into the receiving vessel 12, which is positioned directly at the drive mechanism of the circuit breaker. Due to the short connection paths between the plunger or piston 9 and the receiving vessel 12 the displaced fluid is but I of small volume. Thus, due to the displacement of the fluid, there can be no appreciable flow losses which can interfere with the switching process. The delay caused by the displacement of the hydraulic fluid is negligible and, primarily, equal in all the phases of the circuit breaker, regardless of how far the actuating cylinder is positioned from the common storage unit 14.

In the disclosed embodiment, the hydraulic drive is provided in the lower part of the circuit breaker. However, the circuit breaker of the invention having a single pipeline between the actuating cylinder and the hydraulic storage unit may also be utilized in circuit breakers in which the hydraulic pipeline leads through the stand-off insulator 5 to parts of the drive mechanism at high voltage.

While the invention has been described my means of a specific example and in a specific embodiment, it should not be limited thereto, for obvious modifications will occur to those skilled in the art without departing from the spirit and scope of the invention.

We claim:

1. An electrical high voltage, high capacity circuit breaker having a hydraulic drive including a cylinder, a receiving vessel for displaced hydraulic fluid positioned at the cylinder, a hydraulic system including a storage unit, a valve, and connecting means connecting the receiving vessel to the hydraulic system via the valve, said circuit breaker comprising a single pipeline between the receiving vessel and the hydraulic system, the valve connecting the single pipeline to one of the receiving vessel and the cylinder in dependence upon the pressure in the pipeline.

2. An electrical circuit breaker as claimed in claim 1, further comprising a control valve and means connecting the end of the pipeline away from the receiving vessel to the storage unit via the control valve.

3. An electrical circuit breaker as claimed in claim 2, further comprising a pump and means connecting the pump in shunt with the control valve.

4. An electrical circuit breaker as claimed in claim 2, further comprising a pump, a check valve and means connecting the pump and check valve in series and in shunt with the control valve.

5. An electrical circuit breaker as claimed in claim 2, wherein the control valve releases a constantly acting disconnecting force by connecting the cylinder to the receiving vessel.

6. An electrical high voltage, high capacity circuit breaker having a hydraulic system including a storage unit and having a plurality of phases, each phase having a hydraulic drive including a cylinder, a receiving vessel for displaced hydraulic fluid positioned at the cylinder, a valve, and connecting means connecting the receiving vessel to the hydraulic system via the valve, each phase of said circuit breaker comprising a single pipeline between the receiving vessel of the phase and the' hydraulic system, the valve connecting the single pipeline to one of the receiving vessel and the cylinder of the phase in dependence upon the pressure in the pipeline. 7

7. An electrical circuit breaker as claimed in claim 6, further comprising a control valve and means connecting the pipeline of each phase to the storage unit of the hydraulic system via the control valve. 

1. An electrical high voltage, high capacity circuit breaker having a hydraulic drive including a cylinder, a receiving vessel for displaced hydraulic fluid positioned at the cylinder, a hydraulic system including a storage unit, a valve, and connecting means connecting the receiving vessel to the hydraulic system via the valve, said circuit breaker comprising a single pipeline between the receiving vessel and the hydraulic system, the valve connecting the single pipeline to one of the receiving vessel and the cylinder in dependence upon the pressure in the pipeline.
 2. An electrical circuit breaker as claimed in claim 1, further comprising a control valve and means connecting the end of the pipeline away from the receiving vessel to the storage unit via the control valve.
 3. An electrical circuit breaker as claimed in claim 2, further comprising a pump and means connecting the pump in shunt with the control valve.
 4. An electrical circuit breaker as claimed in claim 2, further comprising a pump, a check valve and means connecting the pump and check valve in series and in shunt with the control valve.
 5. An electrical circuit breaker as claimed in claim 2, wherein the control valve releases a constantly acting disconnecting force by connecting the cylinder to the receiving vessel.
 6. An electrical high voltage, high capacity circuit breaker having a hydraulic system including a storage unit and having a plurality of phases, each phase having a hydraulic drive including a cylinder, a receiving vessel for displaced hydraulic fluid positioned at the cylinder, a valve, and connecting means connecting the receiving vessel to the hydraulic system via the valve, each phase of said circuit breaker comprising a single pipeline between the receiving vessel of the phase and the hydraulic system, the valve connecting the single pipeline to one of the receiving vessel and the cylinder of the phase in dependence upon the pressure in the pipeline.
 7. An electrical circuit breaker as claimed in claim 6, further comprising a control valve and means connecting the pipeline of each phase to the storage unit of the hydraulic system via the control valve. 